On 6/30/26 11:34 AM, Avi Kivity wrote:
On Sat, Jun 6, 2026 at 6:31 PM Avi Kivity <[email protected]
<mailto:[email protected]>> wrote:
From: Avi Kivity <[email protected] <mailto:[email protected]>>
The CWG 2867 implementation introduced conditional cleanup guards for
structured binding base variables, using internal TARGET_EXPRs. These
guard variables are not part of any BIND_EXPR_VARS list, so the
coroutine frame promotion in register_local_var_uses missed them.
After a suspend/resume cycle, the guard's stack location is dead,
causing the conditional destructor to be skipped.
Fix this by introducing TARGET_EXPR_DECOMP_GUARD_P to label
decomposition
cleanup guard TARGET_EXPRs at creation time in cp_finish_decl, then
extending both register_local_var_uses and transform_local_var_uses to
detect them and promote their slots to the coroutine frame.
Ping on this. Is everyone frightened by the A-word?
Yes, at this point we're still being conservative about LLM-generated
patches.
Substantively, this seems like a workaround for an underlying issue with
the collection of variables that need frame promotion; it would be
better to fix to the algorithm, the representation, or both.
But as you suggested, your patch has inspired me to look more closely at
the issue, so I should have a fix soon.
Thanks,
Jason
